A concern for planetary health reflects the fact that global health outcomes are unlikely to be sustainable if they are achieved at the expense of the integrity of the very ecosystems human societies depend on. Indeed, the modern economy appears to treat global health and natural systems as substitutes: as we achieve more of the first, more of the second deteriorates. But there is also a different, under-explored, framing. Ecosystem integrity can be complementary to human health: under specific conditions, investing in the first can lead to improving returns on investments in the second. This is the thesis behind the idea of natural infrastructure. Investing in ecosystems for the purposes of achieving societal objectives, including global health, that can prove to be a good deal for both.

For example, some 2.1 billion people worldwide lack access to safe, readily available water at home, severely undermining health outcomes. With a growing share of the population also facing the effects of environmental degradation, integrated solutions that simultaneously advance nature conservation, water provision, and health would be a critical component of any solution. If these solutions then had the additional property of representing better value for money, they would represent attractive investment opportunities. Thus, including natural infrastructure in the narrative of planetary health requires proving that it is a viable, investable option to address both conservation and health objectives. There are promising examples that give hope. The challenge is to understand how public and private sector investment can fully value the potential of complementarity, and how to design coherent investment strategies that take full advantage of this opportunity at scale.